The Clinton Foundation reported Thursday that it has received as much as $26.4 million in previously undisclosed payments from major corporations, universities, foreign sources and other groups.

The disclosure came as the foundation faced questions over whether it fully complied with a 2008 ethics agreement to reveal its donors and whether any of its funding sources present conflicts of interest for Hillary Rodham Clinton as she begins her presidential campaign.

The money was paid as fees for speeches by Bill, Hillary and Chelsea Clinton. Foundation officials said the funds were tallied internally as “revenue” rather than donations, which is why they had not been included in the public listings of its contributors published as part of the 2008 agreement.

According to the new information, the Clintons have delivered 97 speeches to benefit the charity since 2002. Colleges and universities sponsored more than two dozen of these speeches, along with U.S. and overseas corporations and at least one foreign government, Thailand.

The payments were disclosed late Thursday on the organization’s Web site, with speech payments listed in ranges rather than specific amounts. In total, the payments ranged between $12 million and $26.4 million.

Each week seems to bring more distracting news for Hillary Clinton's presidential campaign, from previously undisclosed payments to the Clinton Foundation to the e-mails she wrote about the 2012 attack in Benghazi, Libya. What does it all mean this time? The Fix's Chris Cillizza explains. (Tom LeGro/The Washington Post)

The paid appearances included speeches by former president Bill Clinton to the Ni­ger­ian ThisDay newspaper group for at least $500,000 and to the Beijing Huaduo Enterprise Consulting Company Ltd., an investment holding company that specializes in the natural gas market, for at least $250,000. Citibank paid at least $250,000 for a speech by Hillary Rodham Clinton.

The disclosures underscore how much the Clintons have leveraged their star power to draw more money not just for their personal enrichment but also for the benefit of their philanthropic work.

The foundation, which has raised $2 billion since Bill Clinton left the White House, has emerged as a political headache for Hillary Clinton amid recent controversies over donations. The foundation, along with the Clintons’ paid speaking careers, have provided additional avenues for foreign governments and other interests to gain entrée to one of America’s most prominent political families. Some Republicans have charged that Hillary Clinton, during her tenure as secretary of state, was in a position to reward foundation donors.

Thursday’s disclosure is one of a number of instances in recent weeks in which the foundation has acknowledged that it received funding from sources not disclosed on its Web site.

The ethics agreement was reached between the foundation and the Obama administration to provide additional transparency and avoid potential conflicts of interest with Hillary Clinton’s appointment as secretary of state.

The agreement placed restrictions on foreign government donations, for instance, but the foundation revealed in February that it had violated the limits at one point by taking $500,000 from Algeria.

Thursday’s release regarding speaking fees follows earlier disclosures showing how the lecture circuit has also made the Clintons personally wealthy.

Last week, Hillary Clinton disclosed that she and her husband made around $25 million since January 2014 from speeches; Bill Clinton also was paid more than $104 million from 2001 through 2012 by delivering speeches.

The Clintons reported that income on federally required personal financial disclosure forms filed by Hillary Clinton as a senator, secretary of state and now a declared presidential candidate.

But the new disclosure indicates that the former president has also spent considerable time speaking on the foundation’s behalf — 73 times since 2002.

Hillary Clinton has delivered 15 such speeches, including one address to Goldman Sachs and another to JPMorgan Chase. Chelsea Clinton, who has taken on an increasingly active role at the foundation, has collected fees for the charity from nine organizations.

The foundation did not provide dates for the speaking engagements.

Vincent Salamone, a spokesman for the Office of Government Ethics, said this week that speeches delivered by public officials or their spouses acting as an “agent” of a charitable group in which the payment is made directly to the organization need not be disclosed in financial filings of public officials.

Brian Fallon, a spokesman for the Clinton campaign, said that analysis explains why the Clintons did not disclose the speeches while Hillary Clinton was a senator and then secretary of state.

While the Clinton Foundation has annually disclosed its donors since 2008, the foundation said Thursday that organizations that paid for Clinton speeches have not before been included in those lists because they were paying for a service and not making a tax-deductible donation.

Craig Minassian, a spokesman for the foundation, said the new release came as part of the foundation’s continuing commitment to transparency. Nonprofit groups are not required by law to release any information about their funders.

“In addition to the more than 300,000 donors who are all listed on our web site, posting these speeches is just another example of how our disclosure policies go above and beyond what’s required of charities,” he said in a statement.

“Like other global charities, the Clinton Foundation receives support from individuals and organizations across all sectors of society, backgrounds and ideologies because they know our programs are improving the lives of millions of people around the world,” he also said.

A foundation official indicated the speech dollars have been disclosed as revenue in annual tax filings to the IRS. The official indicated that the foundation will now update the public speech list four times a year, much as it has said it will do with other donors now that Clinton’s campaign has launched.

The Clintons have indicated that they donate significant personal funds to the foundation each year. The foundation official said that the couple have not considered speech revenue to be part of their personal charitable giving, and Fallon said they have never taken a deduction on their taxes for the fees.

There was one entity clearly associated with a foreign government that provided speaking fees, of $250,000 to $500,000 for a speech by Bill Clinton: The energy ministry in Thailand.

The U.S. Islamic World Forum also provided $250,000 to $500,000 to the foundation for a speech by Bill Clinton, according to the new disclosure. The event was organized in part by the Brookings Institution with support from the government of Qatar.

In addition, the list is studded with overseas corporations and foundations.

They included the South Korean energy and chemicals conglomerate Hanwha, which paid $500,000 to $1,000,000 for a speech by Bill Clinton.

China Real Estate Development Corp. paid the foundation between $250,000 and $500,000 for a speech by the former president. The Qatar First Investment Bank, now known as the Qatar First Bank, paid fees in a similar range. The bank is described by Persian Gulf financial press as specializing in high-net-worth clients.

The Telmex Foundation, founded by Mexican billionaire Carlos Slim, provided between $250,000 and $500,000 for a speech by Hillary Clinton.

The new data shows that a number of public education institutions paid the foundation for speeches by Bill, Hillary or Chelsea Clinton.

Those speeches drew backlash on some campuses, as universities paid hundreds of thousands to the Clinton charity at a time of rising tuitions and slashed university budgets.

After the academic sponsors, financial services and health-industry-related firms heavily populated the list of domestic sponsors.